I x COR YPHODON 207 by Professor Marsh ; the numerous points in common possessed by the members of both families forbid their separation more widely than as families, The earliest types of Amblypoda belong to the genus Pantolanibda, of -which the species P. 'baihinodoii was about four feet in length. As restored it seems to have had proportionately short fore- and hind-limbs, and it had a long tail. It was apparently plantigrade, and would have had not a little likeness to a carnivorous type. The skull has no air cavities, such as are developed in the later types from the Lower Eocene, e.g. CQTIJ- pJiodon ; Pantol&mJbda is from the basal Eocene. The frontal hones show no trace of the horns that are developed in subsequent forms ; the nasals are comparatively long ; the zygomatic arch is slender. The molar teeth are in the primitive form of tritubereuly, and the premolars, as is so often the case with primitive animals, are unlike the molars in form, being less markedly selenodont. As to the vertebral column, the dorsal vertebrae appear to have had short spines, which argues, as it does also in the case of the larger and heavier Coryphodon, a feebleness in the development of ligaments and muscles supporting and moving the head. The scapula seems to have the same peculiar leaf-like form that it has in the later Coryphodon}- This primitive type shows an entepi- condylar foramen in the humerus. It is interesting to observe that the posterior border of the ulna is convex, as in the Creodonts, and in the early Gondylarthrous form JjJ'apt-otogonia. In the sub- sequently-developed Amblypoda, as in the later Condylarthra, that bone acquires a concave outer border. In the* carpus the os centrale is distinct. In the femur the third trochanter is well formed ; it gradually dies out in later Amblypoda. The fibula articulates with the calcaneum. This species, according to Osborn, " typifies the hypothetical Protuiigulate, being more primitive than either JSuprotogQivia or JPhenacodus" 2 The genus Coryphodon is known by a large number of species, of which the first was discovered in this country, and was repre- sented merely by a jaw with some teeth. This was named by Sir R. Owen C. eocaenus, and was dredged up from the bottom of the sea off the Essex coast. A second specimen consisted of a single 1 Tlie scapula of P. bcttfwn&dQn is tiuk.no wu. - For the structure of tills genus and of Coryphodon, see Osborn, JSulL Mus. &a>tę Hist. x. 1898, p. 169.